


Reaching for the Moon

by Hezaia



Series: Reaching for the Moon + High Density [1]
Category: Dr. STONE (Anime), Dr. STONE (Manga)
Genre: Alternate Universe - Canon Divergence, Gen, Humor, Other Additional Tags to Be Added, Overprotective Tsukasa, Protective Tsukasa, Spoilers
Language: English
Status: Completed
Published: 2020-04-10
Updated: 2020-04-10
Packaged: 2021-03-01 19:00:32
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 7,381
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23581993
Author URL: https://archiveofourown.org/users/Hezaia/pseuds/Hezaia
Summary: April 1st 5738: Senku breaks out of his rock prison.Roughly three months later, he gets unexpected company.Unexpected, intrusive, overprotective company.
Relationships: Ishigami Senkuu & Everyone, Ishigami Senkuu & Shishiou Tsukasa
Series: Reaching for the Moon + High Density [1]
Series URL: https://archiveofourown.org/series/1734331
Comments: 17
Kudos: 234





	Reaching for the Moon

**Author's Note:**

> Before this fic gained a title, it was known as the never-ending one-shot, the monstrous one-shot, and the trope bingo fic. I never really intended for it to get this long, and I tried to wrap it up at around 3,000 words, something which I obviously failed. 
> 
> What more tags should I add to this? Feel free to make suggestions :D
> 
> This fic contains an Easter egg of sorts, and the tag for it will be added later on.
> 
> This fic also has an extra, High Density, which features Gen, Ukyo, and some of the stupidity going on behind the scenes.

It was bad luck, plain and simple.

Senku had broken out of his stone prison and started over. Technologically, he was still in the stone age, sure, but he was actually starting to get the hang of it now.

He had some basic tools at his disposal – stone tools, rope and a bow drill. Courtesy of the latter, he also had fire, after quite a bit of effort and tenacity. He also had basic pottery to store things, traps to catch things, clothes to wear, a tree house for shelter, and a laboratory to conduct his experiments.

Simply put, while the situation at hand was not exactly ideal, Senku had it under control. Or rather, he had had it under control. He had had it under control, right up until a foraging trip had suddenly gone down south.

_“Ah-ah, I didn’t prepare for this…”_

Thankfully, Senku had managed to stumble upon one of his traps, because if he had not, then he would have ended up as someone else’s lunch by this point.

Still, while Senku had managed to avoid the most immediate danger of being hunted down and eaten by a pride of lions, he was now suspended fairly high up in the air. This was his most recent trap, where he had gone for the full-on net approach rather than the simpler snare, and Senku was grateful for that, because dangling by one of his limbs would have been even worse than this… which was not to say that this situation was much better, because Senku was still stuck up there, and he could only hope that the big cats down below did not have the jumping or climbing capabilities of other cats, or at the very least, not the brains to use them. Because that would obviously suck; getting mauled by lions, that is.

In any case−

Senku took a deep breath. If he somehow managed to survive this, then making a crossbow would be at the very top of his list. Rather, why hadn’t he done that already? Damn it! He had fucked up! He had−

Senku’s eyes immediately snapped back open at the sound of a roar being abruptly cut short. He looked down and what he saw made him pause, then blink repeatedly. By the time Senku was relatively certain that this was not just some strange hallucination, two lions lay dead on the ground and the rest had fled, leaving behind a tall, muscular and very naked young man.

Was this some primitive caveman or was it someone like Senku – someone that had managed to break free from the petrification? In any case− Too. Damned. Strong. And, also dangerous; there was no mistaking the calculating glint in those dark eyes.

“May I borrow a knife?”

Well, would you look at that – they spoke the same language. That was a plus? Also, yeah, Senku had a knife, and while he wasn’t exactly delighted to part with it, he still pulled it out and dropped it through the net. Because if he did this much, then perhaps the guy would do Senku a favour and help him get down by sawing through the rope down below. Preferably gently as well.

* * *

Senku had newfound appreciation for solid ground once he got down, and by then, his earlier adrenaline rush had already begun to die down, making him intensely aware of the pain in his right ankle. Senku opted not to pay it much heed however, focusing on more immediate things at hand.

The pain had likely showed somehow though – in his expression or in his movements – because in no time, Senku found himself seated upon some rock while Long-Haired Caveman held his foot, gently prodding his ankle.

“Nothing’s broken,” the caveman reported, confirming that his earlier words were neither a fluke nor an auditory hallucination. “Are you hurt anywhere else?”

Tch. “Only my pride.”

Somehow, the caveman seemed to take that comment as an incentive to hurt Senku’s pride a bit more, scooping him up into a goddamned bridal carry, still buck-naked.

“Hey!”

* * *

Encountering the caveman – Tsukasa – was by and large a stroke of luck. That said however−

_“Ah-ah, I didn’t prepare for this…”_

On one hand, with his skills as a hunter, Tsukasa was a definite asset. On the other hand, though− _“Senku?”_ – he was apparently a goddammed exhibitionist.

Also no, it wasn’t that Senku was a prude or anything; he knew what that part of male anatomy looked like, and objectively speaking, Tsukasa appeared to be a fine specimen of a human male in peak physical condition. But that did _not_ mean that Senku wanted to see that guy’s dangly bits whenever the guy returned from having gone fishing.

Speaking of fish though, was that a goddamned shark?

* * *

Senku had some basic tools at his disposal – stone tools, wooden tools, rope, a bow drill and various pots. He also had a theory, and said theory had him collecting nitric acid from old bat excrements and looking into ways of procuring alcohol, because nitric acid alone evidently wasn’t strong enough to have much short-term effects on the−

“So, Senku, what are we using these for?” Tsukasa asked, indicating the shells Senku had made him gather.

“Calcium carbonate,” Senku said, trying to restrain his excitement as he explained how those shells – once crushed and pulverised – could be used to fertilise the soil, to create mortar for building, and to create soap. He put specific emphasis on the latter’s importance in keeping sickness at bay, because that was not to be underestimated. Thankfully, Senku caught himself before he had managed to go into details about how calcium carbonate could also be used in the production of gunpowder, because Senku had a gut feeling that Tsukasa might not be entirely onboard with that – besides, they had only known each other for a couple of days, so there were still things to be revealed about Tsukasa’s character.

“Senku, you’re truly amazing,” Tsukasa said. “I’ve never seen anyone as sharp, smart or quick-witted as you. I respect you from the very bottom of my heart.”

Really, saying that kind of thing with a straight face; what was up with this guy? “A man who flatters another man to his face is either gay or a tactician. What are you trying to say?”

* * *

In hindsight, maybe this was not the best thing he could have said in that particular situation.

But hindsight was twenty-twenty and whatnot.

“Senku.”

“Hm?”

Senku was in his lab, thinking hard. He now had a viable source of alcohol – a bunch of sour grapes – but it would take quite a bit of work to make something out of them. Making wine was one thing, but the alcohol percentage would probably not be enough. Senku would obviously have to distil it, and in order to do that, he obviously needed to make distillation equipment.

Making simple pots and such was obviously one thing. Distillation equipment on the other hand might prove a bit tricky, if not by design then by the fact that it had to be sturdy enough to withstand the heat of the fire.

Because in order to make _nital_ – the industrial grade etching agent that Senku viewed as the key to undoing the whole petrification thing – stronger alcohol would obviously be needed.

Still, considering the time it had taken to do only this much, reviving all of humanity would probably take a fair amount of time, even if more people pitched in to help out. Also, before Senku could even consider trying out the mixture on a human, he would obviously have to check whether or not it worked. The petrified swallows Senku had assembled in his lab would definitely come in handy for that, as he had already used a few to determine that nitric acid alone was not enough to have any short-term effects on the petrification.

Shifting in his seat, Senku turned his head around to look towards the entrance to the lab. There Tsukasa stood, looming like a creepy caveman. But at least he had made a regular habit out of wearing clothes now, so there was always that. “What?”

Tsukasa narrowed his eyes, his mouth set in a firm line as he stepped forth, apparently having invited himself into Senku’s territory, right up to the desk that Senku was currently sitting at.

Senku meanwhile refused to budge, because whatever Tsukasa was on about−

“Un, I was right,” Tsukasa said, running his thumbs over the area below Senku’s eyes. “You haven’t been sleeping again.”

An astute observation from one of the problems that had been keeping him up lately.

Also, what the fuck was up with this blatant invasion of privacy, not to even mention personal space? Hands. Off.

“I’ve stayed awake far longer than this,” Senku scoffed, finally managing to dislodge the hands from his face. “Mind your own damned−”

Again, maybe not the best thing to say, seeing that it resulted in Senku effectively getting dragged out of his seat and thrown over Tsukasa’s shoulder like some damned sack of potatoes. 

And yes, Senku would have flailed a lot harder in an effort to prevent this, had he not recalled the containers of the nitric acid on his desk and opted to not risk them getting spilled, because that kind of thing would have set Senku back _months_ , quite possibly even−

* * *

“Tsukasa.”

“Hm?”

“What the Hell is this supposed to be?”

There was a mildly exasperated huff at that, as if Senku were the one being insufferable. It was really Tsukasa though, because he was the one that had dragged Senku along to his pile of lion hides, laid down on top of it and dragged Senku down to lie down on top of him.

Naturally, Senku wasn’t particularly onboard with this – whatever _this_ was – but the arm wound around his back kept him trapped right where he was, his face plastered against what basically amounted to a human furnace.

Also, said human furnace was stroking his hair, neck and upper back at roughly five-second intervals, which was unnerving, to say the very least.

Really though, Senku could have been literally anywhere else, doing literally anything else. But no, here he was, trapped, right when he seemed to be at the cusp of a breakthrough. He couldn’t stop now, not when he was getting this close, not when he was just about to−

“Rest,” Tsukasa said. “The lab will still be there in the morning.”

Presumably, it would, but so would−

* * *

“Good morning. Want some soup?”

It was a morning, albeit not a very good one. Senku’s body felt stiff all over and his neck felt particularly sore after being at such an awkward angle for so long. Also, it was freezing. Was summer coming to an end already?

He sneezed, and Tsukasa immediately got up.

In next to no time, Senku was sitting by the campfire, bundled up in Tsukasa’s cloak, with a bowl of warm soup in his hands.

It was annoying, sure, but Senku recognised a losing battle when he saw one.

* * *

Also, as it turned out, Tsukasa – the menace – had kept busy in-between… well, the events of the previous afternoon and making soup this morning.

The grapes in the container had been crushed, likely stomped, and there was a new batch of grapes in another basket.

On one hand, Senku could appreciate someone else doing most of the physical labour. On the other hand, though− “For someone who claims that I’m ‘amazing’ and that you respect me, you sure seem to treat me like an incompetent.”

Tsukasa blinked and then narrowed his eyes, his mouth set in a firm line again. “Senku, you−”

A distant but nearing sound drew the attention of both of them; a voice?

Tsukasa immediately got up, grabbing his weapon, and Senku immediately followed suit, shrugging off the heavy cloak.

Senku somehow made it before Tsukasa did; had Tsukasa been running, then the situation would obviously have been different.

_“Senkuuuuuu!”_

Seeing him, Senku laughed for the first time in months. “So, you finally woke up, huh? You big oaf.”

Taiju – wearing some improvised loincloth – let out an excited shout and leapt at him. On one hand, Senku would rather not be subject to an aggressively affectionate hug from his old – and practically butt-naked – friend, but on the other−

The decision was ultimately taken from him, since Tsukasa chose that exact moment to drag Senku out of Taiju’s trajectory.

Taiju ultimately faceplanted on the forest floor, but in a truly Taiju-like fashion, this didn’t even faze him.

“Whoa,” he said, staring at Tsukasa, who had stepped in front of Senku now. Initially, he seemed a bit taken aback, but then, there was a flicker of recognition and his big oafish face was split by a wide, earnest grin. “Whoa, _Strongest High-School Primate, Shishio Tsukasa_?!”

Senku blinked. Strongest High-School what now?

* * *

It was October 5th, in the year 5738 AD, and the known number of de-petrified humans had risen to three. It had been a little more than six months since Senku had broken out, and for Tsukasa, it had been a bit more than three.

As for what determined who woke up and when, Senku’s data was still insufficient. However, with all due likelihood, Senku’s decision to drag Taiju’s statue into the cave with all those bats all those months ago had likely played some part, as had Senku’s initial location just outside that cave.

In turn, this made Tsukasa a major anomaly; Senku knew roughly where the guy’s statue had been, and there had been nothing in the immediate environment that had really stood out. But, whatever reservations Senku might have about Tsukasa’s true character and motives, fact remained that the guy’s de-petrification had come at a pretty convenient time for him.

Then, following all excitement, Taiju’s expression suddenly became sombre.

“What about Yuzuriha and the others?” he asked.

“Well…” Senku said, cracking the back of his neck. “About that…”

* * *

Taiju took on the tasks requiring strength and endurance with great enthusiasm, which in turn freed up more of Tsukasa’s time to hunt. And that was all fine and well, because Senku found it a lot easier to focus on advancing human civilisation without someone looming over him.

“It’s really lucky that Tsukasa’s such a great guy though,” Taiju said, in-between two foraging trips. “I mean, Senku, you’re smart and all, but−”

Gee, thanks for the vote of confidence. Still− “You’re right. I’m the brains, not the brawns.”

* * *

Yuzuriha was neither brains nor brawns – definitely closer to the former than to the latter, sure, but…

“Okay,” she said, once they revived her the next spring. “I’m not entirely sure what’s going on here, but in any case, I’ll do my best!”

* * *

By spring, Senku had finished his crossbow.

By spring, he also had a new hypothesis.

It had really started with Yuzuriha. One of her feet had only partially de-petrified, and there had been limited feeling and mobility in it.

Seeing all the broken statues scattered around the area, Senku had come to wonder if maybe, maybe they could still be revived after all.

The temptation to try out his hypothesis immediately was strong, but Senku had managed to restrain himself, and brought one of his petrified swallows to Tsukasa, asking him to break off its wings.

Then, after fabricating rudimentary glue, the bird had been handed off to Yuzuriha, because such detail-oriented work was really her forte.

And soon, they had their results: Glue and precision plus revival fluid applied to the affected area _was_ enough to revive a bird without compromising its abilities to fly.

As such, it was not unreasonable to assume that the same principle applied even when it came to humans. But who to test it on, considering the limited supply of revival fluid?

“Senku.”

“Hm?”

“I have a request.”

* * *

“Hm…” Senku crouched down, scrutinising the area. “And you’re positive this is the spot?”

“Un, I’m sure the hospital was in this area.”

It was still a fairly wide area, and moreover, even if they decided to dig it out, there was a lot of bedrock in the way. Even with the four of them, and even with Taiju and Tsukasa’s abnormal strength and endurance, it was simply too much work. That was unless−

“Say, Tsukasa… I never did tell you about the fourth use of calcium carbonate, did I?”

Tsukasa was silent for a moment. “No,” he said at last.

Senku found himself on the verge of breaking out into a maniacal grin, because at this point, he didn’t feel like he needed to hold it back.

“By combining it with sulphur, I could make gunpowder,” he explained. “But for this, we’ll obviously need a bit more firepower.”

“Such as?”

Senku laughed. “If I had some sulphuric acid, I could mix it with nitric acid. Adding soap to that, we could get some pretty explosive results!”

“Dynamite?”

“Yeees, one billion points to Tsukasa. Now, any guesses on how to get our hands on some sulphuric acid?”

Taiju thought hard but ultimately shook his head.

Tsukasa said nothing.

Yuzuriha meanwhile cautiously raised her hand. “Maybe Hakone?”

* * *

And so, to Hakone they went.

* * *

And it was a good thing they did, because apparently, there were people there; actual stone-age people, descended from unknown but likely mixed ancestors.

Imagine the things Senku could accomplish if he had that kind of manpower at his disposal.

Sure, obtaining sulphuric acid had been their primary objective for taking this extended road trip, but actually obtaining it would obviously be tricky and if they could cosy up with the locals in the meantime, that wasn’t really anything negative.

Moreover, while none of them had been allowed to set foot inside the village itself, Senku had already seen enough things that would make it worth striking up a partnership, even friendship, with this guy – Chrome – and his impressive mineral collection.

There was also Kohaku, who was sensible and had a fighting prowess that was on par with Tsukasa’s.

Moreover, what united the two of them – Kohaku and Chrome, that is – was the mutual desire to save the sickly Ruri – Kohaku’s older sister, the village’s priestess and storyteller – who obviously had to be sitting on a few clues in regards to the origin of the villagers, as well as to the origin of the village’s curious name. Because− Ishigami village? Really?

So, naturally, Senku wanted to know more about how all that came about, and to get access to this info, he obviously needed access to the priestess and a way to cure or at the very least treat her illness. Besides, it was the decent thing to do, really.

Going by the testimonies of Kohaku and Chrome, the ailment was likely bacterial in nature, in which case, the solution was obviously− _“Sulphanilamide.”_

Everyone – de-petrified humans included – looked at him in confusion.

With a sigh, Senku tried again. _“Antibiotics.”_

Modern humans nodded in understanding.

Stone-Age humans remained confused but looked more curious now. “Antibi-whats?”

Senku tried a third time, adjusting his vocabulary. “It is a type of medicine that kills bacteria. Bacteria and viruses are things that make people sick, and going by what you guys have told me, I believe that Ruri’s illness is caused by bacteria. So, in order to cure her, we need to make and give her this… cure-all medicine.”

“Yes!” Chrome shouted. “Tell me, Senku! How do we make the cure-all medicine?! I’ll totally defeat Ruri’s illness!”

“Yes!” Kohaku agreed. “If it’s to cure my sister, I’ll cooperate however I can!”

* * *

Okay then, first thing: Iron.

Then strong magnets, copper, and phosphorus to get electricity.

And then−

_“Whoa! This is so amazing!”_

Yeah, sure, amazing, but time-consuming.

_“The earth is spinning?! That’s amazing! Tell me more about science, Senku!”_

On one hand, Senku was happy to have encountered someone who was as passionate about science as he was and eager to learn new things at that.

On the other however−

“That is so weird,” Kohaku said. “If the earth is round and it’s spinning, then why am I not thrown off of this branch right now?”

Well, that was obviously due to a thing called gravity.

Senku opened his mouth to explain, but someone beat him to it.

“It’s because of a thing called gravity,” Tsukasa said. “Big things – like the earth, which is a planet – have gravity. Simply put, it means that smaller things are drawn towards them. Gravity is why things fall towards the ground when you drop them and not in any other direction.”

That… was a simple but adequate explanation. Also, that was quite possibly the highest number of words Tsukasa had ever spoken in succession.

_“Whoa, Tsukasa, you’re also a sciencer?!”_

_Scientist._

“No.” Tsukasa shook his head and then looked towards Senku with a smile. “But I did go to grade school.”

Thankfully, Senku was spared from having to explain the Japanese education system, because there were others capable of that.

* * *

Soon, they had iron, and with their makeshift reinvention of ramen, they had enough manpower to power the furnace.

Courtesy of Chromes collection, they also had copper that they could make into wire and after covering the copper wire with lacquer, they could−

“Senku- _chan_.”

“Whaaa−?”

“You’re obviously allergic to lacquer. Let someone else handle it.”

That… sounded fairly reasonable, even if it came from the latest revival, Fake-Mentalist Asagiri Gen. For some reason, Tsukasa had thought that this guy should be among the first to be revived, and Senku hadn’t really seen anything wrong with it, so…

“Come on now, up, up,” the guy persisted. “We need to wash that shit off. Yuzuriha- _chan,_ Chrome _-chan_! I’m leaving this copper wiring thing to you guys!”

* * *

Someone obviously had to have gone off and blabbered to Tsukasa, because by the time Senku and Gen got back from the river, Tsukasa was there. His facial expression bore an eerie resemblance to the thunderclouds rolling in over the horizon.

“Gen.”

Gen immediately straightened up, not bothering with his usual nonsense. “Yes?”

“Handle it.”

_“Yessir!”_

* * *

“So,” Senku said once Tsukasa returned to loom. “Who died and made you king?”

Tsukasa did his usual thing; narrowing his eyes and setting his lips in a thin line. Then he stepped into the newly built laboratory, pulling the curtains shut behind him before turning back around, fixing his gaze upon Senku.

What was up with this – whatever it was? Some display of dominance? Tsukasa’s attempt at intimidation?

Senku wasn’t scared of him though, not any−

A fist collided with the wall just to the left of his head, hard enough to rattle the whole structure. Of course, knowing Tsukasa’s freakish strength, the guy could probably have punched a hole in the wall if he had wanted to.

“No one is dead, but you could have been,” Tsukasa said, his face much too close and his other hand hovering much too close to Senku’s face. Thinking of it now, that guy had pretty long eyelashes for a− Wait, what?

“Dude, overreacting much?” Senku swatted away the hand, gesturing towards his own face. “See, the swelling’s gone down already, so there’s really no reason to−Ah.”

Senku found himself pressed up against the wall, with his wrists pinned and Tsukasa’s forehead pressed up against his.

“For someone who’s so amazing, you’re pretty dumb,” Tsukasa said. “Putting your own health at risk like that, what were you thinking…”

What. In the actual− “Let go.”

Surprisingly, Tsukasa did just that, even stepping back a bit. But he was still looking at him, and there was some kind of emotion in his eyes that Senku struggled to identify.

With a sigh, Senku raked a hand through his hair. “Tsukasa, I’m a scientist, not a mind reader. I don’t understand why you’re acting like this, and frankly, I think you’re overreacting. I wouldn’t die from something like this. Besides, I already promised, didn’t I, that I’d help you with the power of science? Because science−”

“−doesn’t lie. Un, I know.”

That−

Senku looked up. There was something in Tsukasa’s tone, something in his expression, something in the way that he finished Senku’s sentence. Sadness?

Well, whatever. “You guys better have brought me some strong magnets.”

Tsukasa snorted, as if Senku were the one being insufferable. Then he smiled. “We did.”

Well then− “What are we waiting for then? Let’s get on with making the generator!”

And then, once they had electricity, they’d have to figure out how to make glass, and then, gasmasks, and then−

Then sulphuric acid.

* * *

“No.”

This was the entirety of Tsukasa’s response when Senku had announced his and Chrome’s plan to drag one of the village guards, Ginro, along on their expedition for sulphuric acid. And all in all, maybe it was a questionable choice; Ginro might not be a completely lost cause, but bringing him along for the ride simply because of his new and shiny spear that doubled as a sensor for the deadly vapours of sulphuric acid? That was the questionable part.

It could have worked out though, and maybe even had a quite favourable outcome. However, no matter how attached Ginro was to his new and shiny spear, a narrow-eyed look from Tsukasa was enough to have the villager shrink back and stammer out that he didn’t really want to go after all and that he wouldn’t mind lending out his spear and whatnot.

* * *

In any case, they definitely had a close call while getting the sulphuric acid, and at such a time, it was easy to appreciate two things; that Tsukasa was very strong and that he was very, very quick on the uptake.

“Thanks,” Chrome said, having narrowly escaped taking a bath in acid. “For a moment there, I honestly thought I was a goner…”

That made two of them, really, but Tsukasa barely even seemed fazed.

In any case, they had sulphuric acid now, and as such−

* * *

“−I could fix you up with some dynamite if you want, since we’ve already got what we need. I’m sure Yuzuriha and Taiju would be happy to help you out with your sister. I mean, I’d go myself, but right now, I’m a bit…”

A bit busy, to say the very least. The cure-all drug, _sulphanilamide_ , would hardly make itself after all.

* * *

Surprisingly, Tsukasa decided to postpone his long overdue family reunion in favour of sticking around. He also decided to partake in the Ishigami village’s Grand Bout, for reasons best known to himself.

Given the opportunity, Senku might even consider asking Gen about it.

In any case−

“The Winner, Senku!”

−What in the actual fuck?

* * *

In any case, a sickly village priestess got cured, Senku managed to avoid being skewered by an angry mob, and Tsukasa, Tsukasa was… well…

“Look at that pelt! He must be quite a skilled hunter!”

“Yeah, did you see him in the Grand Bout? So strong!”

“And he’s so hot!”

“And devoted too!”

Senku smirked behind his cup of wine, because Tsukasa obviously had to have heard all that, even if the guy stubbornly refused to even acknowledge the three young women – Ruby, Garnet and Sapphire – who were obviously eyeing him up.

The banquet had only gone on for so long, and Tsukasa already looked ready to self-exile to the nearest cave. Hah, served him right.

“Hi, Senku- _chan_ ~” Asagiri Gen flopped down next to him, evidently amused, with a bottle of cola in his hand. “Better keep a close eye on that husband of yours, lest someone might try to steal him away~”

Senku spat out his drink, but some of it did end up in the wrong pipe, triggering a coughing fit. By the time it was mostly over with, he lifted his head back up, fully intent on telling the mentalist to keep his delusions to himself.

However, the face that met his when he looked up was not Gen’s but Tsukasa’s.

“Dude,” Senku said, before the guy really had the time to say or do anything further. “Boundaries.”

* * *

And yeah, and they did finally get some answers in regards to the origin of the curiously named village and the people who inhabited it, so that was one mystery solved. But there were still further mysteries to unravel and further technological advancements to make.

There was also adding to their numbers, and Tsukasa appeared to be taking quite an active part in that. It was sensible though, as was the guy’s decision not to increase their numbers too quickly; winter was still ahead of them, and they needed enough food and shelter to sustain the villagers and the already de-petrified first and foremost.

In any case, they had dynamite, but it would still take additional manpower to dig out statues from the rubble, and while the villagers were generally quite happy to help out, they obviously had to bolster their winter food storages first and foremost, and Senku was keenly aware of that.

That said however, when it came to volunteers, neither Senku nor anyone else really saw much reason to discourage them. Although, in Chrome’s case, him coming along was likely more due to him being curious about the effects of dynamite than him being eager to dig through rubble. Granted, there was likely a perceived obligation to pay Tsukasa back for that time with the sulphuric acid and all, but in any case−

_“That was freaking amaaaaazing! Senku, you gotta teach me how to make that!”_

Senku would very much like to, but he’d better not. Then again, guns aside, making fireworks didn’t sound like such a bad idea; they could be used as a signal to deliver messages over a larger distance, much like−

Senku blinked, suddenly reminded of something Taiju had said during some conversation way back when. Coming to think of it− “A smartphone. We should try making one.”

Well, a cell phone at least.

Chrome tore his eyes away from the destruction; his eyes were glittering. He obviously didn’t know what a smartphone was, but he appeared quite eager to find out.

* * *

In hindsight, maybe heading off to some deep cave to look for rare minerals in the midst of winter hadn’t been their smartest idea in recent months. However, in their defence, tungsten had been the only thing missing from the materials needed to make a phone, and after finding one such rock in Chrome’s extensive mineral collection, how would either of them have been able to resist the temptation?

Besides, Senku, Chrome and Old Man Kaseki had worked hard to advance human civilisation in recent months; since all the things they had made in the process of creating the _sulphanilamide_ , they had, among other things, reinvented Japanese style forging, the saw, the gear, the waterwheel, batteries, a hydroelectric powerplant, pickled food and proper light bulbs.

And, for their most recent escapade, they had geared up with headlamps and pickaxes, and even brought along people to help them lug back whatever treasures they might uncover down there in the cave:

There was Taiju, who had volunteered.

There was also Magma, who had not volunteered.

With these two strongmen at hand, Senku had counted on being able to transport a lot of useful rocks back to the village.

What he had not counted on was, as per usual, Tsukasa’s interference.

* * *

“What are you doing here?” Senku asked, because the question obviously begged to be asked. Not that he wasn’t – to a certain extent – grateful for the assistance; ending up down in a pit with walls threatening to cave in had not been ideal, but with him, Taiju and Magma all stuck down there, this had left Chrome to get them all out.

Said solution had involved funnelling the water of a nearby cave lake into the pit, and it had worked great. If one disregarded the temperature of said water, that is.

With all due honesty, it was a lot worse than Senku had anticipated; hypothermia was setting in a lot more rapidly than expected.

As such, Tsukasa appearing at the edge of the pit with a rope slung over his shoulder had taken a few moments to register, and even then, Senku hadn’t been quite sure that he wasn’t seeing things.

But the rope, the rope had been pretty damned tangible, even if Senku’s fingers had been too stiff to get a good enough grip on it. Naturally, they had also been too stiff to make decent knots, so naturally, that task had fallen onto another.

“You’re such a weakling,” Magma muttered under his breath. “Too damned skinny.”

Taiju obviously heard it though, because his face broke out into a wide grin; neither of the two seemed to be quite as affected by the cold as Senku was. It was unfair, really.

It was an indignity, but Senku could take it, knowing it would get him out of the water even just a tiny bit sooner than the others.

“I was built for brains, not for brawns,” Senku just said, trying to keep his teeth from clattering. “What can I say? Both of them are−”

The rope was pulled tight and secured, and Senku let out a pained gasp. He wasn’t even being pulled up yet, and that was bound to hurt. Maybe Senku should have gone along with Magma’s suggestion instead; Magma could have used his crazy strength to throw him, and even if the angle had not been sufficient, the only real risk would have been− “Ugh.”

“It’s okay, Senku,” Taiju assured him. “We’ll support you as much as we can.”

And by support, he obviously meant it quite literally: Taiju had gotten up on Magma’s shoulders, and was now standing there, providing Senku with footing for a while longer.

The whole ordeal was over fairly quickly though; Chrome already had a small campfire going by the time Tsukasa pulled Senku out.

And, having done that, Tsukasa wasted no time.

* * *

Hypothermia generally required immediate medical assistance. However, in this stone world where there were no real doctors at hand, there was only applying first aid treatment and hoping for the best.

The first step was providing shelter from the elements, moving the person to a warm, dry place.

The second was removing wet clothing, and while Senku wasn’t exactly thrilled at being stripped, he still allowed it, because he very much preferred to keep his clothes intact. Because knowing Tsukasa, he’d definitely cut them off if he saw the need.

Next was putting the person on a blanket or something to insulate them from the ground, in addition to covering their whole body – head included – with blankets, leaving only the face clear for the sake of monitoring respiration and administering the appropriate measures if it ceased.

Senku was breathing fine though, so he relayed instructions to get the others out. Surprisingly, this command was actually obeyed; Tsukasa vanished off to pull the others out, but once that had been accomplished, he was immediately back again, obviously ready to execute the next step.

“Dude, are you freaking serious? Do we seriously have to do this?” Senku asked.

Tsukasa’s response consisted of removing his shirt – his signature cloak had already been dumped on top of Senku – indicating that yes, he was indeed freaking serious about the whole skin-to-skin contact thing.

* * *

“Senku…”

“What?”

“Tell me what to do next.”

Well, Senku would very much like Tsukasa to provide him with additional personal space, but with the situation at hand, one simply had to bear with the invasion. Besides, Tsukasa had kept his pants on for this one, so Senku obviously had to give him some credit for that one.

“Well,” Senku said at last. “Hot water and similar heat sources are out, because that can damage the skin and potentially trigger a cardiac arrest. Rubbing and jarring movements should also be avoided, as they might also lead to cardiac arrest. Warm drinks are fine though, if the person is conscious.”

And Senku was most definitely conscious, and he most definitely intended to stay that way. Because, if he just nodded off for one sec, who knew what kinds of ideas these guys might get? Tsukasa aside, Taiju was definitely the sort that might jump right into performing CPR if he believed the situation called for it.

And, while Senku might have preferred Taiju if he’d been able to choose who would be acting as his personal heater, Senku would rather not risk having him perform any CPR – which was not to say that Senku really−

“Soup.”

Chrome immediately got to work on it.

* * *

Thankfully, after that whole fiasco, something very rewarding awaited them.

_“A skarn deposit!”_

Naturally, other than Senku, only Chrome seemed to understand the magnitude of what they had just found. Thankfully though, the other three didn’t really need to understand; they just needed to use their brutish strength to break out the ore Senku desperately needed.

Tungsten, manganese, chalcopyrite, zinc blende…

It was, as Chrome had put it, freaking awesome.

* * *

Unfortunately, there was an end to all good things, and even if they had five people who could carry things – three of whom could carry a lot – they would not be able to bring the whole skarn deposit back home, not even in pieces. It was a shame, really, but there was always next time. That said however−

“Guys, what’s the rush?!”

The one asking was Chrome, but Senku definitely shared the sentiment; neither had been truly ready to leave the cave and its plethora of rare minerals, but suddenly everyone else had started packing up and herding them towards the exit. Like sure, Chrome and Senku both had a sack of rocks each, but compared to the others–

“Oh, that’s right!” Taiju exclaimed. “Today’s a special day after all!”

A special day?

Well, it was January 4th, so technically, Senku’s birthday, but other than that, there was really no– Oh. “Hoh? Will there be some type of special event?”

Predictably, Taiju opened his mouth to answer.

Less predictably, Magma covered his mouth, forcing his jaw back shut.

Hoh, Senku was curious now.

* * *

It was a telescope – no, an observatory – and the mastermind was none other than− “Hiya, Senku- _chan_! I hope you like the present. Everyone helped~”

−Asagiri Gen.

“It’s quite a present, I admit,” Senku said, because indeed, it was. “Did your cola supply run out again or something? This is a pretty big present, considering I haven’t really done anything big.”

The Mentalist tilted his head slightly to one side. “Are you reeeeeeally sure about that though?”

* * *

Well, technically speaking, Senku had done a lot of things. And now he had tungsten and other rare minerals at his disposal, which meant that he would be able to do even more.

That said, if they wanted to make a cell phone, then they obviously needed gold wire, and in order to get that− “We need to make a cotton candy machine.”

And in order to make cotton candy, they needed sugar, and thankfully, they already had some of that. It likely wouldn’t be enough though, so they’d obviously have to extract some from wine or something similar.

In any case− “You’re making a cell phone?”

“Yeah, that’s the plan. Figured we might need it sometime in the near future.”

The guy – one of the people Tsukasa had revived – let out a snort. Like Tsukasa, he had a tendency to loom, but unlike Tsukasa, he covered most of his face. He also carried around a spear and obviously knew how to use it.

That obviously didn’t mean that Senku cared a whole lot if he had the guy’s approval or not; the guy – Hyoga – could go off and live as a caveman for all that Senku cared.

But, somehow, since that dynamite thing, Senku hadn’t quite been able to shake the feeling that the guy had developed a keen interest in him and his inventions.

Senku meanwhile had developed a fleeting interest in the guy’s weapon. It was hard _not_ to notice it after all, with Hyoga always bringing that thing along. Senku was almost willing the bet the guy even slept with it.

In any case− “That thing; could I get a closer look?”

Hyoga eyed him like he was a particularly intriguing specimen.

“I don’t like people touching my things,” Hyoga said at last. “But for you, I’m willing to make an exception.”

Hoh? Well then−

Senku moved closer, giving the thing a quick onceover. “ _Kudayari_ , huh? You’re quite skilled.”

“Yes,” Hyoga acknowledged. “I would say the same about you, Senku.”

A man who flatters another man to his face is either gay or tactician. In this case, it was safe to say that they both fell firmly into the latter category. In any case− “You want something, right? Let’s hear it.”

* * *

“What are you doing, Senku- _chan_ ~?”

Mixing graphite – chimney soot, that is – with alcohol, in other words− “Making lubricant.”

_“Lubricant?!”_

Senku looked up, one part annoyed and the other part impressed – with the Mentalist’s vocal range, that is. “Yeah.”

“Making lube?” Gen leaned in, lowering his voice into an almost conspiratorial whisper. “That’s unexpectedly forward of you, Senku- _chan_ ~”

Senku stared. This idiot, what was he insinuating? “Solid lubricant, made by moistening graphite with alcohol. Putting the carbon crystals on a smooth surface makes it slippery. Hyoga asked me to make it.”

_“Hyoga did?!”_

This time around, the vocal range was not just impressive; Gen’s voice was so shrill it was actively hurting Senku’s eardrums. _“What the heck are you screaming for, Mentalist?”_

Gen opened his mouth, but surprisingly no sound came out. Rather, he looked almost−

“Yes, what seems to be the problem, Gen?”

Up until this point, Senku had only seen the Mentalist appear genuinely fretful once, and that was that time when Tsukasa− Well, in any case− “I’m almost done with this. Want to test it out now or later tonight?”

Hyoga’s eyes crinkled.

* * *

It was amazing just how much of a difference a piece of bamboo with its insides coated in solid lubricant could do when added to Hyoga’s spear. It increased his speed significantly.

“I must admit, it actually slides quite nicely,” Hyoga said, having bested the village’s best fighters in a spar. “I am quite satisfied.”

Well, now that that was over with−

Senku snorted softly, finally turning his head to acknowledge the looming presence behind him. “So, what do you want?”

It wasn’t that chilly out, and Senku was wearing weather-appropriate attire, so−

“A sword.” Tsukasa smiled. “Will you make one for me?”

A… sword? “Right… what would you need that for?”

Also, that was more of Old Man Kaseki’s territory, no?

“Well,” Tsukasa said, and surprisingly, he wasn’t even looking at Senku, or even at Hyoga or the others as they headed back towards the village. Instead, he was looking skywards, towards the full moon. “I figured it might prove useful, to some degree.”

To what degree? Was he planning something, or just preparing for contingencies? In any case− “Sure, why the Hell not?” Senku said, rising to his feet. “Let’s get on with it.”

And really, why not get started right away? In the morning, Senku would be mostly occupied with other things after all.

And while occupying himself with those thoughts, Senku managed to walk a fair distance before stopping and glancing over his shoulder to confirm that Tsukasa was still where he had left him, staring up at the moon.

“Oi, Tsukasa!” Senku called out. “Are you coming or not?”

It didn’t take Tsukasa very long to catch up; he didn’t even appear slightly winded. It was unfair, really. That said however−

“Coming to think of it, you sure follow me around a lot,” Senku said. “You don’t need to, you know. You don’t really owe me anything. You’ve helped me out and I’ve helped you out, so, in short, we’re even. So−”

Tsukasa snorted softly. Then he spoke, and his words made Senku stop in his tracks.

“Senku,” he said. “I’ll follow you anywhere – to the edge of the earth, even to the moon.”

Saying that kind of thing with perfect sincerity – what was up with this guy, really?

Still− “That’s reassuring.”

In a way.

In another, not entirely. In any case− “Additional manpower is always welcome.”

And additional brainpower too.


End file.
